It is a chronic necrotizing infection of bronchi & bronchioles causing abnormal permanent dilation of these airways. Image Link

Bronchiectasis is usually thought of as a disease of large airways because this is the location of the obvious lesions.

However, the origin in most instances lies in the obliteration of peripheral airways. 

Often the cause is clearly obstruction of central bronchi by inhaled foreign bodies, tumour, mucus plugs in asthma and compressive lymphadenpathy .

The last condition is best recognized in the right middle lobe, where the bronchus is long and narrow, has little cartilage support, and is surrounded by a cuff of lymph nodes.

Enlargement of these lymph nodes, particularly by tuberculosis, leads to obstruction of the bronchus, atelectasis, and bronchiectasis, a situation described as the “right middle lobe syndrome”.

However, with the decrease in the incidence of tuberculosis and the increase in lung cancer, the right middle lobe syndrome is now most commonly due to cancer.

Bronchiectasis is also a feature of cystic fibrosis and ciliary dyskinesia.

Bronchiectasis was once common, usually resulting from such childhood bronchopulmonary infections as measles and pertussis or from bacterial infections.

Vaccines and antibiotics have dramatically reduced the frequency and the importance of bronchiectasis.

Nevertheless, one half to two thirds of all cases of bronchiectasis follow a bronchopulmonary infection, hence the term “post infective bronchiectasis”.

 At present, the most common cause of bronchiectasis is adenovirus infection.

The disease is brought about by a severe inflammation of bronchi and bronchioles, which results in destruction of the walls of the central bronchi and bronchioles.

With the consequent collapse of lung parenchyma (atelectasis), the bronchi dilate.

 Inflammation of the central airways leads to hypersecretion of mucus and abnormalities of the surface epithelium, including an increased number of goblet cells.

A vicious cycle is set up because a pool of mucus is liable to further infection, which leads to progressive destruction of the bronchial walls.

Gross examination: Image1 ; Image2

In 1950, Reid (8) described three types of bronchiectasis. The bronchial dilatation are of varying shapes and  is classified as saccular (cystic), varicose, fusiform (cylindrical).

 In the saccular form, the proximal third to fourth branches of the bronchi (the segmental bronchus is the first branch) are severely dilated and end blindly, and there is extensive collapse and fibrosis of lung parenchyma.

In varicose bronchiectasis, the bronchi resemble varicose veins when  with irregular dilatation and constrictions. Two to eight branchings of bronchi are recognized grossly, bronchiolar obliteration is not as severe, and parenchymal abnormalities are most variable.

In cylindrical bronchiectasis, the bronchi show uniform slight dilatation. Many such cases are examples of bronchitis and emphysema.

Bronchiectasis is most common in the lower lobes, the left more commonly involved than the right, and usually bilateral. The dilated bronchi contain thick mucopurulent secretions.

Microscopic features:  Image 1  ; Image2

1. Mild to necrotizing acute & chronic inflammation of bronchi and bronchioles.

2. Necrosis destroys bronchi & broncheolar walls, producing lung abscess.

3. Chronic cases show peribronchial fibrosis.

There is destruction of all components of the bronchial wall, chronic inflammation, a disproportionate number of goblet cells, and squamous metaplasia of the epithelium.

 Lymphoid follicles are often seen in the bronchial walls.

The distal bronchi and bronchioles are scarred and often obliterated.

 The bronchial arteries increase in size and supply the inflamed bronchial wall and fibrous tissue. Consequently, hemoptysis is a common symptom.

Clinical presentation: Typically, a patient with bronchiectasis has a history of a severe, recurrent bronchopulmonary infection in childhood and thereafter has chronic productive cough, often with mucopurulent sputum and fever.

Radiologically, the affected lung is small, bronchi are crowded together, and the bronchial walls may be visible. The definitive diagnosis is made bronchographically (by instillation of radiographic contrast medium into the lung). Morphologically, the abnormalities are more extensive than visualized radiographically.

Treatment:  Surgical resection is more palliative than curative, and although persistence of symptoms and progression of lesions are common, significant functional abnormalities are unusual.

 It should be noted that acute, reversible dilatation of bronchi may occur as a consequence of bacterial or viral bronchopulmonary infection, and it may take months before the bronchi returns to normal size.

This is important to recognize because such patients do not require surgery.

Complications:

1. Cor pulmonale ; 2.  Metastatic abscesses ; 3.  Amyloidosis.

Bronchiectasis often complicates cystic fibrosis.

Pulmonary complications are the most serious manifestation of cystic fibrosis, which is heritable disorder affecting mucus secretion and eccrine sweat glands.

The bronchial mucus is thick and patients are particularly liable to infection with pseudomonas aeruginosa.

As a result, bronchial and bronchiolar obliteration lead to bronchiectasis. 

Kartagener syndrome:

Kartagener syndrome (KS), an autosomal recessively inherited disease, is characterized by the  triad of dextrocardia (with or without situs inversus), bronchiectasis and sinusitis.

 It is now apparent that the syndrome may be due to a variety of structural and functional abnormalities of cilia (the immotile cilia), or ciliary dyskinesia, syndrome).

 These abnormalities are heritable, the most common of which is deficiency of the dynein arms. Others include radial spoke deficiency (Sturgess syndrome) and an abnormal complement of doublets.

 Since cilia throughout the body are deficient, sterility in both males and females is usual, because of immotility in the vas deferens and the fallopian tube.

In the respiratory tract, ciliary defects lead to upper and lower respiratory tract infection in the lung and to bronchiectasis identical with “postinfective bronchiectasis”.

 

PULMONARY PATHOLOGY Acute Respiratory Distress Syndrome Bronchiolitis Bronchial Asthma Pulmonary Alveolar Proteinosis Pulmonary edema Respiratory syncytial virus infection Chronic Bronchitis Pulmonary Infection Pnuemococcal Pneumonia Haemophilus influenza Infection Klebsiella Pneumoniae Mycoplasma Pneumonia Pneumocystis Pneumonia Cytomegalovirus infection Legionellosis  (Legionnaires' Disease)